gopls: add WorkspaceFiles option

WorkspaceFiles allows an end-user to specify a set of files which, when
modified, will trigger a full reload of any views currently open in a
session. This is especially important for users who use custom
GOPACKAGESDRIVERS, as previously, you were forced to restart the
language server in order to get up-to-date diagnostics in some certain
instances.

Change-Id: Iba7a6137cb0b88a59318217a9a28d079100192a4

Author: rv32ima

gopls/doc/settings.md

@@ -143,6 +143,17 @@ This setting is only supported when gopls is built with Go 1.16 or later.
 
 Default: `["ignore"]`.
 
+<a id='workspaceFiles'></a>
+### `workspaceFiles []string`
+
+workspaceFiles configures the set of globs that match files defining the logical build of the current workspace.
+Any on-disk changes to any files matching a glob specified here will trigger a reload of the workspace.
+
+This setting need only be customized in environments with a custom GOPACKAGESDRIVER. By default, this will look
+for changes to every go.mod / go.work file in your workspace.
+
+Default: `["**/*.{mod,work}"]`.
+
 <a id='formatting'></a>
 ## Formatting
 

gopls/internal/cache/session.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"maps"
 	"os"
 	"path/filepath"
 	"slices"
@@ -773,6 +774,25 @@ func (s *Session) DidModifyFiles(ctx context.Context, modifications []file.Modif
 	// changed on disk.
 	checkViews := false
 
+	// Hack: collect folders from existing views.
+	// TODO(golang/go#57979): we really should track folders independent of
+	// Views, but since we always have a default View for each folder, this
+	// works for now.
+	var folders []*Folder // preserve folder order
+	workspaceFileGlobsSet := make(map[string]bool)
+	seen := make(map[*Folder]unit)
+	for _, v := range s.views {
+		if _, ok := seen[v.folder]; ok {
+			continue
+		}
+		seen[v.folder] = unit{}
+		folders = append(folders, v.folder)
+		for _, glob := range v.folder.Options.WorkspaceFiles {
+			workspaceFileGlobsSet[glob] = true
+		}
+	}
+	workspaceFileGlobs := slices.Collect(maps.Keys(workspaceFileGlobsSet))
+
 	changed := make(map[protocol.DocumentURI]file.Handle)
 	for _, c := range modifications {
 		fh := mustReadFile(ctx, s, c.URI)
@@ -783,12 +803,7 @@ func (s *Session) DidModifyFiles(ctx context.Context, modifications []file.Modif
 			checkViews = true
 		}
 
-		// Any on-disk change to a go.work or go.mod file causes recomputing views.
-		//
-		// TODO(rfindley): go.work files need not be named "go.work" -- we need to
-		// check each view's source to handle the case of an explicit GOWORK value.
-		// Write a test that fails, and fix this.
-		if (isGoWork(c.URI) || isGoMod(c.URI)) && (c.Action == file.Save || c.OnDisk) {
+		if isWorkspaceFile(c.URI, workspaceFileGlobs) && (c.Action == file.Save || c.OnDisk) {
 			checkViews = true
 		}
 
@@ -815,20 +830,6 @@ func (s *Session) DidModifyFiles(ctx context.Context, modifications []file.Modif
 	}
 
 	if checkViews {
-		// Hack: collect folders from existing views.
-		// TODO(golang/go#57979): we really should track folders independent of
-		// Views, but since we always have a default View for each folder, this
-		// works for now.
-		var folders []*Folder // preserve folder order
-		seen := make(map[*Folder]unit)
-		for _, v := range s.views {
-			if _, ok := seen[v.folder]; ok {
-				continue
-			}
-			seen[v.folder] = unit{}
-			folders = append(folders, v.folder)
-		}
-
 		var openFiles []protocol.DocumentURI
 		for _, o := range s.Overlays() {
 			openFiles = append(openFiles, o.URI())
@@ -1084,12 +1085,12 @@ func (b brokenFile) Content() ([]byte, error)  { return nil, b.err }
 // keep the server's state up to date.
 //
 // This set includes
-//  1. all go.mod and go.work files in the workspace; and
+//  1. all files defined by the WorkspaceFiles option in BuildOptions (to support custom GOPACKAGESDRIVERS); and
 //  2. for each Snapshot, its modules (or directory for ad-hoc views). In
 //     module mode, this is the set of active modules (and for VS Code, all
 //     workspace directories within them, due to golang/go#42348).
 //
-// The watch for workspace go.work and go.mod files in (1) is sufficient to
+// The watch for workspace files in (1) is sufficient to
 // capture changes to the repo structure that may affect the set of views.
 // Whenever this set changes, we reload the workspace and invalidate memoized
 // files.
@@ -1114,12 +1115,8 @@ func (b brokenFile) Content() ([]byte, error)  { return nil, b.err }
 func (s *Session) FileWatchingGlobPatterns(ctx context.Context) map[protocol.RelativePattern]unit {
 	s.viewMu.Lock()
 	defer s.viewMu.Unlock()
-
 	// Always watch files that may change the set of views.
-	patterns := map[protocol.RelativePattern]unit{
-		{Pattern: "**/*.{mod,work}"}: {},
-	}
-
+	patterns := map[protocol.RelativePattern]unit{}
 	for _, view := range s.views {
 		snapshot, release, err := view.Snapshot()
 		if err != nil {

gopls/internal/cache/snapshot.go

@@ -799,6 +799,10 @@ func (s *Snapshot) fileWatchingGlobPatterns() map[protocol.RelativePattern]unit
 		patterns[workPattern] = unit{}
 	}
 
+	for _, glob := range s.Options().WorkspaceFiles {
+		patterns[protocol.RelativePattern{Pattern: glob}] = unit{}
+	}
+
 	extensions := "go,mod,sum,work"
 	for _, ext := range s.Options().TemplateExtensions {
 		extensions += "," + ext
@@ -1560,6 +1564,11 @@ func (s *Snapshot) clone(ctx, bgCtx context.Context, changed StateChange, done f
 			reinit = true
 			break
 		}
+
+		if isWorkspaceFile(mod.URI, s.view.workspaceFiles) && (mod.Action == file.Save || mod.OnDisk) {
+			reinit = true
+			break
+		}
 	}
 
 	// Collect observed file handles for changed URIs from the old snapshot, if

gopls/internal/cache/view.go

@@ -182,6 +182,9 @@ type viewDefinition struct {
 
 	// envOverlay holds additional environment to apply to this viewDefinition.
 	envOverlay map[string]string
+
+	// workspaceFiles are the set of files that will trigger this view to be re-initialized
+	workspaceFiles []string
 }
 
 // definition implements the viewDefiner interface.
@@ -830,6 +833,7 @@ func defineView(ctx context.Context, fs file.Source, folder *Folder, forFile fil
 
 	def := new(viewDefinition)
 	def.folder = folder
+	def.workspaceFiles = folder.Options.WorkspaceFiles
 
 	if forFile != nil && fileKind(forFile) == file.Go {
 		// If the file has GOOS/GOARCH build constraints that

gopls/internal/cache/workspace.go

@@ -13,6 +13,7 @@ import (
 	"golang.org/x/mod/modfile"
 	"golang.org/x/tools/gopls/internal/file"
 	"golang.org/x/tools/gopls/internal/protocol"
+	"golang.org/x/tools/gopls/internal/test/integration/fake/glob"
 )
 
 // isGoWork reports if uri is a go.work file.
@@ -60,9 +61,18 @@ func localModFiles(relativeTo string, goWorkOrModPaths []string) map[protocol.Do
 	return modFiles
 }
 
-// isGoMod reports if uri is a go.mod file.
-func isGoMod(uri protocol.DocumentURI) bool {
-	return filepath.Base(uri.Path()) == "go.mod"
+func isWorkspaceFile(uri protocol.DocumentURI, workspaceFiles []string) bool {
+	for _, workspaceFile := range workspaceFiles {
+		g, err := glob.Parse(workspaceFile)
+		if err != nil {
+			continue
+		}
+
+		if g.Match(uri.Path()) {
+			return true
+		}
+	}
+	return false
 }
 
 // goModModules returns the URIs of "workspace" go.mod files defined by a

gopls/internal/cmd/capabilities_test.go

@@ -152,7 +152,7 @@ func TestCapabilities(t *testing.T) {
 		}
 		// The item's TextEdit must be a pointer, as VS Code considers TextEdits
 		// that don't contain the cursor position to be invalid.
-		var textEdit = item.TextEdit.Value
+		textEdit := item.TextEdit.Value
 		switch textEdit.(type) {
 		case protocol.TextEdit, protocol.InsertReplaceEdit:
 		default:

gopls/internal/doc/api.json

@@ -92,6 +92,19 @@
 				"Status": "",
 				"Hierarchy": "build"
 			},
+			{
+				"Name": "workspaceFiles",
+				"Type": "[]string",
+				"Doc": "workspaceFiles configures the set of globs that match files defining the logical build of the current workspace.\nAny on-disk changes to any files matching a glob specified here will trigger a reload of the workspace.\n\nThis setting need only be customized in environments with a custom GOPACKAGESDRIVER. By default, this will look\nfor changes to every go.mod / go.work file in your workspace.\n",
+				"EnumKeys": {
+					"ValueType": "",
+					"Keys": null
+				},
+				"EnumValues": null,
+				"Default": "[\"**/*.{mod,work}\"]",
+				"Status": "",
+				"Hierarchy": "build"
+			},
 			{
 				"Name": "hoverKind",
 				"Type": "enum",

gopls/internal/settings/default.go

@@ -86,6 +86,7 @@ func DefaultOptions(overrides ...func(*Options)) *Options {
 					DirectoryFilters:        []string{"-**/node_modules"},
 					TemplateExtensions:      []string{},
 					StandaloneTags:          []string{"ignore"},
+					WorkspaceFiles:          []string{"**/*.{mod,work}"},
 				},
 				UIOptions: UIOptions{
 					DiagnosticOptions: DiagnosticOptions{

gopls/internal/settings/settings.go

@@ -155,6 +155,13 @@ type BuildOptions struct {
 	//
 	// This setting is only supported when gopls is built with Go 1.16 or later.
 	StandaloneTags []string
+
+	// WorkspaceFiles configures the set of globs that match files defining the logical build of the current workspace.
+	// Any on-disk changes to any files matching a glob specified here will trigger a reload of the workspace.
+	//
+	// This setting need only be customized in environments with a custom GOPACKAGESDRIVER. By default, this will look
+	// for changes to every go.mod / go.work file in your workspace.
+	WorkspaceFiles []string
 }
 
 // Note: UIOptions must be comparable with reflect.DeepEqual.
@@ -979,6 +986,8 @@ func (o *Options) setOne(name string, value any) error {
 		}
 		o.DirectoryFilters = filters
 
+	case "workspaceFiles":
+		return setStringSlice(&o.BuildOptions.WorkspaceFiles, value)
 	case "completionDocumentation":
 		return setBool(&o.CompletionDocumentation, value)
 	case "usePlaceholders":